1. Field of the Invention
The present invention relates generally to trench digging and pipe laying equipment, and more particularly to an adjustable coupling connector for use in attaching equipment to an excavator, wherein the equipment includes a pipe laying tool and a compaction wheel.
2. Brief Description of the Prior Art
The process of laying sections of pipe for an underground pipe line involves first digging a trench to the required depth with a shovel attached to an excavator. The shovel is then removed from the excavator and a pipe laying tool is attached to the excavator for lowering the pipe into the trench. The pipe laying tool is then removed from the excavator and replaced with a shovel for use in depositing the required filler over the pipe. The shovel is then removed and a compaction wheel is attached for compacting the filler. Various methods of attaching the shovel, compaction wheel and pipe laying tool to the excavator are used. At the present time there is no standard connector for attaching tools to an excavator. If the excavator can accommodate the compaction wheel but not the pipe laying tool, the pipe may be secured to an end of an arm or boom of the excavator with chains and chokers. A disadvantage of this method is that it is necessary to place a worker in the trench to guide the newly lowered section of pipe into contact with a previously installed section. The worker must also disengage the chains, etc. from the pipe. The task of manipulating the pipe in the trench is not without some hazard, due in part to the weight of the pipe and excavator arm. In deep trenches, the additional hazard of possible collapse of the trench walls must be carefully guarded against for the safety of the trench worker. In cases where there is danger of wall collapse, shoring is often put up in place to support the soil. The shoring must then be removed and reinstalled for the process of laying the next section or sections of pipe, etc.
U.S. Pat. No. 5,232,502 by Recker describes an apparatus designed to lay pipe with an excavator without the need for a worker in the trench. A horizontally positioned arm 78 is suspended from the working end of an excavator boom assembly, attached with a rotary coupler 76 (FIG. 2 and col. 3, lines 3-32). In order to avoid the need for a worker in the trench to apply pipe sealant, a sealant is forced through the rotary coupler and sprayed from the end of the horizontal arm. The apparatus as described has some disadvantages and is not in common use. The rotary couple with conduit is not a standard quick coupler, and requires special modification of the excavator. Connecting the horizontal arm 78 and conduit requires a second worker, or alternatively the excavator operator has to leave the cab to manually perform the operation. Positioning the arm 78 and support beam 80 in the process of connecting the tool to the excavator arm assembly is also a problem due to the weight of the tool, and the fact that without other support, the tool could only lay on the ground, 90 degrees disoriented, requiring an operator, probably with additional equipment to lift it into position for connecting to the excavator coupling device 70. In addition, the rotary connection 76 is not durable enough to withstand repeated use, or rigid enough to allow undesired rotation of a pipe placed on the arm 78. For example, a typical eight foot section of 54 inch diameter concrete pipe weighs about 1,370 pounds per foot, or a total of 10,960 pounds. A much more rigid and strong connection is required for practical use.
It is apparent that an improved tool and method of laying pipe is needed that keeps workers out of the pipe trench, and that is robust and can be used with a standard excavator arm quick coupling device. It is also apparent that a coupling device is needed that can accommodate a range of different excavator coupling apparatus.
It is therefore an object of the present invention to provide a connector that can be adjusted for a range of sizes of excavator coupling apparatus.
It is an object of the present invention to provide a tool for use in lowering a section of pipe into a trench that avoids the use of chains and chokers that must be removed by a trench worker.
It is another object of the present invention to provide a tool for laying pipe that is rugged in construction and that can be attached to the working end of an excavator boom assembly by an excavator operator without leaving the excavator cab.
It is a further object of the present invention to provide a tool that facilitates the joining of pipe sections without the need for a trench worker.
Briefly, a preferred embodiment of the present invention includes an adjustable connector for accommodating a range of mating excavator couplers. The adjustable connector includes two parallel bars to which the excavator coupler clamps. One of the bars is fixed in position to risers extending from a connector base. Each end of the other bar is attached to a point off center of a circular plate so that as the plate is rotated, the bar moves laterally relative to the bar axis. The plates are rotatably positioned in holes in the risers, and captivating side plates are welded to the risers for covering a portion of each plate, securing the plates from movement parallel to its axis but allowing the plate to rotate. Holes in the circular plates and side plates are provided, and a bolt is placed through each of the side plates and circular plates for securing each circular plate in a fixed position.
An advantage of the adjustable connector apparatus of the present invention is that it can accommodate a range of excavator coupler sizes.
An advantage of the tool of the present invention is that it allows a pipe to be positioned in a trench with improved accuracy.
A further advantage of the tool of the present invention is that it allows a pipe supported by the tool to be joined to another pipe in a trench without the need for a trench worker.
A still further advantage of the present invention is that it reduces worker injury by avoiding the need for a worker in the trench during the pipe laying operation.
Another advantage of the present invention is that it provides a pipe laying tool that is self supporting, and does not require an excavator operator to leave the excavator cab to connect the tool.